Hydraulic motors

ABSTRACT

This invention relates to a hydraulic motor constituted by a cylinder block mounted to rotate in a support, by two groups of cams integral with said support, by rollers integral in translation with pistons contained in the cylinders of the cylinder block and in abutment on said cams, and by a valve coaxial with the axis of the cylinder block and provided with a slide for selecting the running conditions of the motor, with three positions, each cylinder comprises a pipe connecting it successively to a plurality of orifices disposed in two groups, which each correspond to a group of cams, and the orifices of the same group are regularly distributed on the valve, whilst the orifices of the group of orifices corresponding to the first group of cams comprise first and second orifices, which are alternately placed in communication, the first orifices with a first conduit connected to a source of pressurised fluid, or a discharge tank, the second orifices, which follow the first orifices, with a second conduit connected to the discharge tank or the source of pressurised fluid, respectively, and the orifices of the group of orifices corresponding to the second group of cams comprise third and fourth orifices, which are alternately placed in communication, respectively and selectively, by means of the selection slide, the third orifices with the first conduit, or with the second conduit, or with the fourth orifices, which follow said third orifices, and the fourth orifices with the second conduit, or with the first conduit, or with said third orifices.

United States Patent [191 Martin 1 HYDRAULIC MOTORS [76] Inventor: Louis E. Martin, Residence Brichebay, Senlis, France [22] Filed: Feb. 28, 1972 [21] Appl. No.: 230,013

[30] Foreign Application Priority Data Mar. 2, 1971 France 71.07153 [52] US. Cl 91/492, 91/498, 91/413 [51] Int. Cl. ..F01b 1/06 [58] Field of Search 91/474, 491, 492, 497, 91/498, 6.5, 413, 414

[56] References Cited UNITED STATES PATENTS 2,442,125 5/1948 Gunning 91/413 3,403,599 10/1968 Guinot 91/491 2,562,363 7/1951 Nixon 91/473 3,357,312 12/1967 Rogov et al.... 91/498 3,296,937 1/1967 Guinot 91/474 3,593,621 7/1971 Praddaude 91/498 3,369,457 2/1968 Guinot l l 91/491 2,650,543 9/1953 Pauget 417/214 FOREIGN PATENTS OR APPLICATIONS 18,601 2/1969 Japan 91/501 Primary ExaminerWi1liam L. Freeh Assistant Examiner-Gregory P. La Pointe Attorney, Agent, or Firm--Fitzpatrick, Cella, Harper & Scinto [451 May 7, 1974 [5 7] ABSTRACT This invention relates to a hydraulic motor constituted by a cylinder block mounted to rotate in a support, by two groups of cams integral with said support, by rollers integral in translation with pistons contained in the cylinders of the cylinder block and in abutment on said cams, and by a valve coaxial with the axis of the cylinder block and provided with a slide for selecting the running conditions of the motor, with three positions, each cylinder comprises a pipe connecting it successively to a plurality of orifices disposed in two groups, which each correspond to a group of cams, and the orifices of the same group are regularly distributed on the valve, whilst the orifices of the group of orifices corresponding to the first group of cams comprise first and second orifices, which are alternately placed in communication, the first orifices with a first conduit connected to a source of pressurised fluid, or a discharge tank, the second orifices, which follow the first orifices, with a second conduit connected to the discharge tank or the source of pressurised fluid, respectively, and the orifices of the group of orifices corresponding to the second group of cams comprise third and fourth orifices, which are alternately placed in communication, respectively and selectively, by means of the selection slide, the third orifices with the first conduit, or with the second conduit, or with the fourth orifices, which follow said third orifices, and the fourth orifices with the second conduit, or with the first conduit, or with said third orifices.

2 Claims, 9 Drawing Figures 1 HYDRAULIC MOTORS The present invention relates to a method for obtaining particular running conditions of a hydraulic motor, and motor for carrying out the method.

It will firstly be specified that the expression hydraulic motor means the different hydraulic machines which, connected to a hydraulic circuit and provided with a shaft connected to a rotor, function effectively as motor, when the pressure of the fluid is higher in the admission conduit than in the delivery conduit, and when the shaft is then driven by the rotor, and which operate as pump, when on the contrary the pressure of the fluid is higher in the delivery conduit than in the admission conduit, and when the shaft then drives the rotor. For convenience of language, we are keeping the single expression motor for designating the abovementioned machines.

There are already a number of types of hydraulic motors, certain of which comprise speed changing devices which enable them, whilst being fed at constant output, to have two or three speeds of rotation of the shaft. Thus, in a given type of motor, the cams of said motor have been divided into at least two groups, and, with the aid of a selection slide valve, either the cylinders disposed opposite the first group of cams or those disposed opposite the second group, or the cylinders disposed opposite the two groups, are fed in parallel. If the strokes of the two groups of cams are equal, two possible speeds of rotation are obtained; if they are unequal, the number of possible speeds of rotation is three.

What is generally sought after in a multi-speed motor is a wide span between the two extreme speeds. Now, it is technologically very difficult to produce such a motor, the dimensions of the different parts not being easy to select. In fact, one of the extreme speeds is obtained, when all the cylinders are fed and the sum of the strokes is effected, whilst the other extreme speed is obtained by feeding only the cylinders disposed opposite the short stroke cams. However, it is necessary to make the rollers (and the other elements) not only so that they may cooperate with the short stroke cams, but also with the large stroke cams. This state of affairs leads to an obligatory excess dimensioning of certain parts, and to a poor use of the material.

In order to remedy these disadvantages, and easily to obtain very different extreme speeds, the earlier necessity of making cams with very different strokes should be eliminated, and a motor should be chosen which has perhaps different cams, but the characteristics of which are conventional and normal, so as to render these cams easy to make.

To this end, a process is therefore applied for obtaining particular running conditions of a hydraulic motor comprising two groups of cams, according to which, in order toobtain a first running, the cylinders disposed opposite the cams of at least one of the two groups of cams are fed with fluid, whilst, when the cylinders disposed opposite the cams of the two groups of cams are fed with fluid, this latter feed is effected by connecting said cylinders in parallel.

In order to obtain the particular running conditions, the cylinders disposed opposite the cams of the two groups of cams are fed with fluid by effecting the connection of the feeds of the cylinders disposed opposite the cams of a first group of the two groups of cams in opposition with the feeds of the cylinders disposed opposite the cams of the second group of cams.

The invention also, and more particularly, has for its object a hydraulic motor for carrying out the preceding method and constituted by a cylinder-block mounted to rotate in a support, by two groups of cams integral with said support, by rollers integral in translation with pistons contained in the cylinders of the cylinder block and in abutment on said cams and by a valve coaxial with the axis of the cylinder block and provided with a slide for selecting the running conditions of the motor with three positions. Each cylinder comprises-a pipe connecting it successivelyto a plurality of orifices disposed in two groups, each of which corresponds to a group of cams, the orifices of the same group being regularly distributed on the valve. The orifices of the group of orifices corresponding to the first group of cams comprise first and second orifices, which are alternately placed in communication, the first orifices with a first conduit connected to a source of pressurised fluid or to a discharge tank, the second orifices, which'follow the-first orifices, with a second conduit connected to the discharge tank, or to the source of pressurised fluid, respectively. The orifices of the group of orifices corresponding to the second group of cams comprise third and fourth orifices, which are alternately placed in communication, respectively, and sele'ctively by means of the selection slide, the third orifices with the first conduit or with the second conduit, or with the fourth orifices, whichfollow said third orifices and, the fourth orifices with the second conduit, or with the first conduit, or with said third orifices.

According to a preferred embodiment of the invention, the selection slide is cylindrical, coaxial with the valve and capable of being displaced in translation parallel to its axis opposite five grooves made in said valve. Said grooves are in permanent communication, the first with the fifth, the second with the first conduit, and the fourth with the second conduit, and are in selective communication, in the first position of the slide, the first groove with the second, and the third with the fourth, in'the second position of the slide, the second groove with the third, and the fourth with the fifth, and, finally, in 'the third position of the slide, the third groove with the fourth and the fifth groove, and the second groove being isolated from theother grooves.

The first groove is advantageously placed in permanent communication with'the fifth groove by means of a complementary pipe arranged in the valve.

Furthermore, it is also advantageous if the sections of the different pistons contained in the cylinders are identical, whilst the first stroke of axial clearance of a piston, whose roller is in abutment on the cam of the first group of cams and is displaced between a summit and a notch of said cam, and the second stroke of axial clearance of a piston, whose roller has been displaced between the summit and the notch of a cam of the second group of cams, have unequal values.

The two groups of cams preferably contain the same transverse plane perpendicular to the axis of rotation of the cylinder block, whilst the cams of the two groups are continuously connected and follow one another, alternately, a cam of the first group, then a cam of the second group.

ln addition, it is often advantageous if the angle of rotation, which enables the zone of abutment of the roller of a pistonto be displaced froma summit or a notch of a camof the first group of cams to the following summit or notch of the same cam of said first group, and the angle of rotation which enables the zone of abutment of the roller of a piston to be displaced from a summit or a notch of a cam of the second group of cams to the following summit or notch of the same cam of said second group, have unequal values.

The values of said angles of rotation are then determined as a function of the values of corresponding strokes of the pistons.

Finally, it is advantageous if the slide of the valve is connected to a hydraulic device for adjusting its position.

The invention will be more readily understood upon reading the following description with reference to the accompanying drawings, in which:

FIGS. 1, 2 and 3 are diagrams relative to the three possible running operations of a motor according to the invention;

FIG. 4 is an axial section of a motor according to the invention;

FIG. 5 is a part transverse section along V-V of FIG. 4 through the motor shown in FIG. 4.

FIGS. '6, 7, 8 and 9 are transverse sections along VI- VI, VII-VII, VIII-VIII and lXlX respectively, of FIG. 4, through the valve and slide of the valve of the motor shown in FIG. 4.

The method-according to the invention firstly consists in making a hydraulic motor inknown manner, giving it two groups of cams, of generally different strokes, which are generally referenced by C and C C being greater than C and each group having the same number of cams as the other group. The following operation consisted in the production of separate feeds for the two imaginary motors constituted by the cylinders momentarily disposed opposite the cams, of the first group of cams for the first motor, the second group of cams for the second motor. Of course, the abovementioned imaginary motors, which correspond to groups ofcylinders of the same real motor, in fact possess only one single rotor. This arrangement will be specified later.

As a function of the position of the selection slide which the valve comprises, in manner known per se, one of the three running conditions described hereinbelow may be chosen.

In the first position of the slide, the first running illustrated in FIG. I is obtained. The imaginary motors l and 2 have their respective inlets 3 and 4 connected in parallel to a first conduit 5, itself connected to a source of pressurised fluid in direction of arrow F, or further are both connected in parallel to a second conduit 6,

itself connected to the element complementary of the one to which conduit 5 is connected, in the present case either to the discharge tank in direction of arrow G, or to the source of pressurised fluid in direction of arrow F. Under these circumstances, the feed flow F being constant, the speed of rotation of the complete real motor is inversely proportional to the sum C, C of the strokes C, and C the pistons of the real motor all having the same section. The lowest of the speeds of rotation of the motor is obtained.

In the second position of the slide, the functioning illustrated in FIG. 2 is obtained. The connection of the preceding conduits 4 and 8 is the only difference with respect to the connection of FIG. 1. In fact, it is conduit 8 which is connected in parallel to the conduit 3, these two conduits 3 and 8 then being connected to conduit 5, whilst the conduits 4 and 6 are both connected to conduit 7. Nevertheless, C, having been chosen to be greater than C the rotor of the motor still rotates in the same direction as before, and the flow which feeds the motor 1 is then equal to the sum of the constant feed flow and a flow proportional to C since the delivery of the motor 2 also feeds motor 1. In other words,

the speed of rotation of the complete real motor is, this time, inversely proportional to the difference C -C of the strokes C, and C The highest speed of rotation of the motor is obtained. Furthermore, it will be noted on this subject that it is even possible, by making C greater than C,, to reverse the speed of rotation which the motor has during its first running.

It will further be specified that the running, illustrated in FIG. 2, is the particular running which had never been obtained before. It enables, with cams of strokes C close to C a very high speed of rotation of the motor to be obtained, said cams being furthermore of any type and not being particularly difficult to manufacture with respect to the conventional cams.

Finally, a third running of the motor may easily be obtained by effecting the connections of FIG. 3. The inlet and delivery conduits 4 and 8 of the motor 2 are connected and consequently only motor 1 is in fact fed, with the feed flow coming from the source of pressurised fluid. In practice, the conduits 4 and 8 are connected to a complementary conduit 9, which is itself connected to conduit 5, but which in fact plays no active role in the present connection. The speed of rotation of the motor obtained in the course of this running is inversely proportional to the stroke C and has a value which is intermediary between the values of the speeds obtained during the two running conditions described hereinabove. By way of indication, it will be noted that the conduit 7 nowfconstitutes one and the same conduit with the second conduit connected either to the discharge tank or to the source of pressurised fluid.

In order to carry out the method that has just been described, the invention proposes the type of motor described hereinafter with reference to FIGS. 4 to 9.

The motor shown is constituted by a cylinder block 10, which is mounted to rotate in a casing 11 with which cams I2 and 13 of two different types are integral. The cams l2 and 13 are disposed in the same transverse plane in order to cooperate with the rollers 14 which are integral in translation with the pistons 15 mounted to slide in cylinders 16, arranged in the cylinder block 10 and disposed radially in said cylinder block. A cam 13 with large stroke C follows a cam 12 with small stroke C being continuously connected to the section of the two cams 12 disposed on either side of said cam 13. The motor shown comprises three cams l2 and three cams 13.

A cylindrical valve 17 is integral .in rotation with the casing 11, except for a small clearance for adjustment.

The cylinder block 10 is thus mounted to rotate with respect to this valve. Orifices are made on the outer periphery 17a of the valve 17, and are so disposed that they are in alternate communication with the cylinders 16 by conduits 18 connecting said cylinders to the inner periphery 10a of the cylinder .block 10. The

above-mentioned orifices correspond in twos to a cam 12 or 13 and are in fact of four distinct types: orifices l9 and 20, which correspond to cams 13, and orifices 21 and 22 which correspond to earns 12.

Furthermore, a selection slide 23 which is cylindrical and coaxial with the valve 17, is mounted to slide axially in said valve. The slide 23 is held in its central position by a spring 24, interposed between two discs 25 connected to said slide, and may be displaced on either side of this central position, in order to be disposed in two other positions, by admission of pressurised fluid in one of the two chambers 26 or 27 located at the ends of the slide by a conduit 28 or 29, and placed in communication with a discharge tank of the other chamber 27 or 26, by means of the other conduit 29 or 28. This device for adjusting the position of the slide is therefore of hydraulic nature and may be remotely controlled.

It will be specified that the slide 23 comprises three shoulders 30, 31, 32 which are displaced opposite five grooves 33, 34, 35, 36 and 37, made in the valve 17. In its first position, the slide 23 is pushed entirely to the right, the pressurised control fluid being present in the chamber 26. The chambers35 and 36 communicate together in the same way as chambers 33 and 34, the shoulders 31 and being in positions permitting these communications. In the second position of the slide, the latter is on the contrary pushed completely towards the left, the pressurised control fluid then being contained in the chamber 27. The various shoulders then occupy such positions that the grooves 34 and 35 communicate together, similarly to the grooves 36 and 37. Finally, when the slide is disposed in its third position or central position, being held there only by the action of the spring 24, the shoulders 30 and 31 isolate the groove 34 from the grooves 33 and 35, whilst grooves 35, 36 and 37 are placed in communication.

Furthermore, it will be noted that the groove 34 is in permanent communication with the conduit 5 by a conduit 38 made in the valve 17, the groove 36 is itself in permanent communication with the conduit 6 by a conduit 39 made in the said valve 17, andfinally a conduit 40 also arranged in the valve 17, permanently connects the end grooves 33 and 37. I

The sections shown in FIGS. 6 to 9 show the communications ensured inside the valve 17 itself.

In FIG. 6, it will be noted that three conduits 38 connect the groove 34 to the different orifices 20 and to the conduit 5, the conduit 5 being in fact divided into two in order to permit a better flow of the inlet or delivery flow of the fluid to be conveyed.

In FIG. 7, three conduits 39 are shown and connect the various orifices 19 to the groove 36 (and to conduit 6), the conduit 6 also being divided in two for the same reasons as conduit 5.

Finally, in FIGS. 8 and 9, orifices 21 and 22 are placed in communication, respectively, with corresponding grooves 35 and 33, by conduits 41 and 42.

It will further be noted that the sections of the cams l2 and 13 are defined as being homokinetic. This signifies the fact that, when the cylinder block rotates at a given speed of rotation, the sum of the linear speeds of the pistons disposed opposite the cams of the same group is substantially constant, this having for its advantage to procure the constancy of the inlet and delivery flows of the fluid contained in the cylinders relative to said pistons.

from one summit 43 to the following one are unequal on the earns 12 and 13. In particular, in the example shown, the shift A12 corresponding to a cam 12 with small stroke C is smaller than the shift A13 relative to a cam 13 of large stroke C This non-imperative arrangement is, however, advantageous for the reasons that will be given later. It will simply be noted straight away that the shifts A12 and A13 are determined as a function of the values of strokes C and C The motor that has just been described, which already enables the process according to the invention to be carried out, has other advantages which will be seen in the course of the following description of the running obtained.

When the slide 23 is disposed in its first position (pushed entirely towards the right), the running shown in FIG. 1 is obtained. In fact, the communications of grooves 33 and 34 on the one hand and 35 and 36 on the other hand correspond, according to what is shown in FIGS. 6 and 9 on the one hand and 7 and 8 on the other hand, to the communications of the orifices l9 and 21 with conduit 6, and orifices 20 and 22 with conduit 5. An examination of FIG. 5 shows that the cylinders are indeed connected in parallel opposite the cams of the two groups of cams.

When the slide 23 is pushed towards the left, in its second position, the communications of the grooves 34 and 35, and 36 and 37, bring about the communications (see FIGS. 6 and 8, and 7 and 9), of the orifices 20 and 21, and 19 and 22. Thus, the cylinders disposed opposite the cams of the two grooves of cams are connected in opposition, which is shown in FIG. 5, and the connection corresponding to the running shown in FIG. 2 is effected. It is precisely the particular running sought after which is obtained.

Finally, when the slide 23 is in its central position, the groove 34 is isolated, whilst the grooves 35, 36, 37 and 33 are in communication. This arrangement corresponds to the communication of the orifices 20 with the conduit 5 (FIG. 6) and orifices 19, 21 and 22 with conduit 6 (FIGS. 7, 8 and 9). Referring now to FIG. 5, it is ascertained that .the present arrangement corresponds to the shortcircuiting of the feed of the cylinders disposed opposite the earns 12, and finally to the single active feed of the cylinders disposed opposite the cams 13 with large stroke C The running conditions shown in FIG. 3 is thus obtained.

The motor which has been described is however easy to manufacture. In particular, the earns 12 and 13 are commonplace and do not have to have very small strokes for the difference between the extreme operational speeds of the motor to be obtained. In fact, these speeds are associated only with the ratio (C l C (C, C which may be very large, although C and C keep usual values.

It will be noted on this subject, that in certain particular cases, it is even possible, by providing C to be smaller than C to obtain a reversal of the direction of rotation of the motor, without having to provide special arrangements.

Furthermore, the spread of the section of a cam 13, with large stroke C over an angle A13 greater than angle A12 relative to the cam 12, makes it possible to limit the values of the rising and descending accelera;

I fices, arranged to be alternately placed in communications of the rollers 14 and the pistons 15 along the sec'- tion of said cam 13. Therefore heavy and expensive reinforcements of the different elements do not have to be made, and the best possible use is made of the material.

Finally, the advantages of the hydraulic control of the position of the slide 23 are sufficiently known per se for it to be necessary to emphasize same.

It will further be specified that numerous variants may be made to the motor that has been described. For example the cams l2 and 13 could be disposed, not in the same transverse plane asin the example shown, but in two distinct transverse planes, one plane containing the cams l2 and the second plane containing the cams 13.

The motors according to the invention may be used in many ways, such as, inter alia, the propulsion of public works machines at a low speed and a high speed.

What is claimed is:

l. Hydraulic motor comprising a cylinder block mounted to rotate in a support, two groups of cams integral with said support, each group of cams being formed to produce a different piston displacement, rollers integral in translation with pistons contained in cylinders formed in the cylinder block and in abutment on said earns, a valve coaxial with the axis of the cylinder block, said valve being provided with a slide for selecting the running conditions of the motor, each cylinder having a conduit associated therewith a conduit connecting it successively to each of a plurality of orifices disposed in two groups, each'of which correspond to a different group of said cams, with the orifices of the same group being regularly distributed on the valve, the orifices of the group of orifices corresponding to the first group of cams comprising first and second orition with a first conduit connected to a source of pressurized fluid and a second conduit connected to a discharge tank respectively, and the orifices of the group of orifices corresponding to the second group of cams comprising third and fourth orifices arranged to be alternately placed in communication, via said selecting slide, with the first and second conduits, said slide being shiftable from one position, placing the third orifices in communication with first conduit and the fourth orifices in communication with the second conduit, to a second position, placing the third orifices in communication with the second conduit and the fourth orifices in communication with the first conduit, said selection slide being cylindrical, coaxial with the valve, and capable of being displaced in translation parallel to its axis opposite five grooves made in said valve, whilst said grooves are in permanent communication, the first groove with the fifth groove and with said fourth orifices, the second groove with one of said conduits and with said second orifices, the third groove with said third orifices, and the fourth groove with the other of said conduits and with said first orifices, and are in selective communication, in the first position of the slide, the first groove with the second, and the third groove with the fourth groove, in the second position of the slide, the second groove with the third groove, and the fourth groove with the fifth groove, and, finally, in the the valve,

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 808,951 Dated May 7, 1974 In ento- -(s) LOUIS E. MARTIN It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Front page, after item {76] identifying the-inventor,

insert Societe Anonyme: POCLAIN, Le Plessis-Belleville (Oise) France [73] Assignee:

Signed and sealed this 8th day of October 1974.

(SEAL) Attest:

McCOY M. GIBSON JR. 0. MARSHALL .DANN Attesting Officer Commissioner of Patents OmM PC4050 (10-69) USCOMM-DC 00376-P69 U. 5 GOVERNMENT PRINTING OFFICE [9.9 0-358-334, 

1. Hydraulic motor comprising a cylinder block mounted to rotate in a support, two groups of cams integral with said support, each group of cams being formed to produce a different piston displacement, rollers integral in translation with pistons contained in cylinders formed in the cylinder block and in abutment on said cams, a valve coaxial with the axis of the cylinder block, said valve being provided with a slide for selecting the running conditions of the motor, each cylinder having a conduit associated therewith a conduit connecting it successively to each of a plurality of orifices disposed in two groups, each of which correspond to a different group of said cams, with the orifices of the same group being regularly distributed on the valve, the orifices of the group of orifices corresponding to the first group of cams comprising first and second orifices, arranged to be alternately placed in communication with a first conduit connected to a source of pressurized fluid and a second conduit connected to a discharge tank respectively, and the orifices of the group of orifices corresponding to the second group of cams comprising third and fourth orifices arranged to be alternately placed in communication, via said selecting slide, with the first and second conduits, said slide being shiftable from one position, placing the third orifices in communication with first conduit and the fourth orifices in communication with the second conduit, to a second position, placing the third orifices in communication with the second conduit and the fourth orifices in communication with the first conduit, said selection slide being cylindrical, coaxial with the valve, and capable of being displaced in translation parallel to its axis opposite five grooves made in said valve, whilst said grooves are in permanent communication, the first groove with the fifth groove and with said fourth orifices, the second groove with one of said conduits and with said second orifices, the third groove with said third orifices, and the fourth groove with the other of said conduits and with said first orifices, and are in selective communication, in the first position of the slide, the first groove with the second, and the third groove with the fourth groove, in the second position of the slide, the second groove with the third groove, and the fourth groove with the fifth groove, and, finally, in the third position of the slide, the third groove with the fourth groove and the fifth groove, the second groove being isolated from the other groove.
 2. Motor as claimed in claim 1, wherein the first groove is in permanent communication with the fifth groove by means of a complementary pipe arranged in the valve. 